Valence Aware Dictionary and sEntiment Reasoner (VADER) [1]} is a lexicon and rule-based sentiment analysis tool. It does not require any training data and is constructed from a generalized, valence-based human-curated gold standard sentiment. It is fast and gives positive, negative, neutral and an overall sentiment score. It is especially effective for more casual posts (as in free-form text) and is especially useful for mining sentiments of social media posts, YouTube comments, etc.
